Jan Mischke

14 Questions 32 Answers 0 Followers

Questions related from Jan Mischke

Adhesion problems of Al/Ni on p-GaN after RIE etching?

Hello, I am trying to structure p-GaN-layers by RIE-etching. Therefor I use a 200 nm Al/ 200 nm Ni etching mask. However, after the etching process (ICP plasma, I use Cl and N2 suring the etching...

13 March 2019 134 4 View

Why don't I see a 2D-Peak in Graphene while D-Peak is present?

Hello, This is a more theoreticall question: The D and 2D band correspond to the same phonon (iTO @ K-point). So it's the same breathing mode. How come, that I can have different Raman spectra...

19 March 2018 3,524 7 View

Increasing sheet resistance in graphene after annealing step?

Hello Community, I am struggeling at the moment with the correct concept of the link between the sheet resistance of graphene and the improvement of the dirac point after a annealing step. So...

16 January 2018 9,901 0 View

Origin of non-emitting regions above a "insulating" substrate in a CH4/H2 plasma?

Hello Community, I am working with a CH4/H2 Plasma in a cold-wall reactor. If I use conducting substrates (like metalls) there is a homogeneous plasma visible above my substrate (roughly 1-2 cm...

19 October 2017 2,005 2 View

Where does the dark space in plasma above non-conducting substrate come from?

Hi, I am using a pulsed DC plasma (~10 kHz pulsing frequency) with CH4 and H2 in a simple plate condenser set up. I use pressures of a few mbar and temperatures of 700°C-900°C. If I use non...

01 June 2017 8,016 5 View

Where is the difference in Hall measurements between 3D and 2D samples?

Hello, Hall measurements with Hall bar geometries are well understood for bulk materials. My question is: Can you translate the common bulk equations for RH, the carrier concentration and...

02 February 2017 6,853 6 View

What are these strange structures during graphene growth?

I am growing graphene on copper foil and then transfering it on SiO2-substrate. If I have a look onto it with SEM I see these strange structures. Raman says that the brighter spots are graphene...

14 November 2016 1,559 5 View

Why does the Balmer-series in a H2-plasma decrease with increasing CH4 amount?

Hi, I am investigating a H2+CH4-Plasma with OES. I am trying to find out what the origin of the processes behind the OES peaks are. I start by igniting a 200 sccm H2 plasma with 800V and ~150W....

06 November 2016 7,670 8 View

How to improve the structural and electrical poperties of ZnO nanocrystal films?

I am trying to characterize ZnO nanocrystal films out of nanoparticles deposited via spin coating (ca. 35nm thickness) on a glass substrates coated with ITO. The films have a lot of "holes" (round...

05 July 2016 6,467 9 View

Raman spectroscopy of CVD Graphene directly on as grown Copper foil?

Hi, I am trying to characterize some PECVD Graphene samples on copper foil. Because transfer on SiO2 substrates is a time intensive process, I would rather try to characterize the samples via...

09 June 2016 5,987 13 View

How can you physically describe the different slopes in the Space Charge limited Current (SCLC) model?

One of my problems is to fully understand the principle of the space charge limited current model. - the process of trapping: after the ohmic region, at the point where the concentration of free...

22 January 2015 3,095 4 View

How can I achieve ohmic contacts to p-GaN core-multishell nanowires?

I am trying to contact core-multishell GaN nanowires with a n-doped core and a p-doped multishell radial around the core via E-Beam lithopraphy. To characterize them I tried to realize ohmic...

11 December 2014 1,512 7 View

Where does the contrast in SEM images of 2D-Materials come from?

I am trying to understand the contrast difference between 2D-Materials (namels graphene) and the underlying susbtrate (e.g. SiO2 or germanium). Using an SE2-detector you get topographical...

01 January 1970 5,453 3 View

Dependency of the plasma power in a H2 plasma from the H2:CH4 ratio?

Hello Community, I am currently trying to grow graphene via plasma enhanced chemical vapor deposition. Therefore I use a reactor with a pulsed DC plasma source. During my plasma tests I made some...

01 January 1970 7,768 10 View